Field of the Disclosure
Embodiments of the present disclosure generally relate to magnetic storage elements, and more particularly to memory cells in a magnetoresistive random-access memory device (MRAM).
Description of the Related Art
MRAM is a non-volatile random-access memory technology. Unlike conventional RAM, data in MRAM devices are not stored as electric charge or current flows. Rather, data is stored by magnetic storage elements. MRAM devices include cells or elements having a magnetically hard layer (i.e., a “reference” layer) and a magnetically soft layer (i.e., the “free” layer). Writing to MRAM is performed by passing current through current leads that are formed on either side of each memory element in order to create a local induced magnetic field, which sets the direction of the soft layer magnetization. Significant problems arise when scaling these devices to high densities. Particularly, the currents required to generate sufficient field to switch the free layer become prohibitively large, and disturbances to neighboring cells or elements can occur during writing, which in turn may cause a neighboring cell to be erroneously written.
Spin transfer torque (STT) MRAM devices are similar to conventional MRAM devices except that the write current paths pass through the magnetic layers of each memory element. The free layer is set via the spin transfer torque from the spin polarized current passing through the reference magnetic layer.
Spin orbit torque (SOT) MRAM devices are similar to STT-MRAM devices except that the read and write paths are independent. Because the write current does not pass through the reference and free magnetic layers, SOT-MRAM devices can have better endurance.
As high density nonvolatile memory devices become increasingly more popular in diverse applications, there is a continual need for improved MRAM devices. Thus, what is needed is an improved SOT-MRAM device with an improved chip design and improved potential memory density limitations.